A 2008 article in Archives of Internal Medicine teaches us the role of regular physical activity in keeping lost weight from returning to once-overweight women.
201 overweight women (body mass index 27-40) aged 21 to 45 wanted to lose excess weight. They were sedentary at baseline, exercising fewer than three days a week for under 20 minutes. Sound familiar? Depending on baseline weight, the participants were assigned to eat either 1200 or 1500 calories per day, and to exercise according to one of four different exercise programs. Exercise recommendations were to burn a certain number of calories per week (1000 or 2000 calories) at either moderate or vigorous intensity. There were weekly group meetings for discussion of eating and exercise for the first six months, twice monthly meetings during the next 6 months, and monthly for the next six months. There was telephone contact for between months 19 to 24. This is pretty intense contact. Each participant was given a treadmill to use at home, but my impression is that other forms of exercise were permitted and discussed.
Ten subjects were excluded from follow-up analysis, mostly because they got pregnant. Nineteen others lost interest and dropped out.
Participants self-reported their physical activity levels.
At 24 months into the study, 170 of the original 201 participants were able to provide objective weight loss data.
Of the 170 subjects available for full analysis at 24 months, 54 either gained weight or lost none. Thirty-three lost 0 to 4.9% of initial body weight, 36 lost 5 to 9.9% initial body weight, and 47 (24.6%) lost 10% or more of initial body weight. (Who says diets don’t work?)
People who lost 10% or more of initial body weight at 24 months reported performing more physical activity – 275 minutes a week – compared with those who lost less than 10% of initial body weight. This amount of exercise equates to 55 minutes of exercise on five days per week above the baseline level of activity, which was sedentary as you recall. Whether they were assigned to “moderate” or “vigorous” exercise intensity didn’t seem to matter. Whether they actually performed at the assigned level is unclear.
These women who sustained a weight loss of 10% or more of initial body weight at 24 months were burning 1835 calories a week in physical activity.
Women who lost less than 10% of initial body weight, or lost no weight, exercised an average of 34 minutes a day on five days a week.
By 24 months, participants on average had regained about half of the weight they had lost during the first six months [which is typical].
After six months of dieting, many people start to regain half of what they lost. We saw this phenomenon recently in the Israeli study of low-fat vs low-carb vs Mediterranean diet.
If you have a lot of excess fat to lose, you have to wonder if it would make sense to start a different diet program every six months, until you reach your weight goal. Maybe there’s something about the novelty and excitement of a new diet program that keeps you motivated and disciplined for six months. For someone with lots of weight to lose, I wonder if they’d do better switching to a new diet every six months.
The authors note there are few similar long-term studies examining the amount and intensity of physical activity needed to improve weight loss success. So this is important new information.
In using exercise to help prevent weight regain, it may not matter whether the exercise is moderate or intense.
The authors write:
…the inability to sustain weight loss appears to mirror the inability to sustain physical activity.
Long-term sustained weight loss is possible for a significant portion of overweight women. Although most women won’t do it, success is enhanced by exercising for 55 minutes on five days a week. Most men won’t exercise that much either. Which camp do you fall into?
For physical activity instruction and information, visit Shape Up America!, Physical Activity for Everyone, or Growing Stronger: Strength Training for Older Adults.
Reference: Jakicic, John M., et al. Effect of Exercise on 24-Month Weight Loss Maintenance in Overweight Women. Archives of Internal Medicine, 168 (2008): 1,550-1,559.